Both hard and soft contact lenses require regular and careful cleaning in order to maintain their usefulness. In particular, the cleaning techniques employed must preserve the efficacy and safety of the lens.
To remain efficacious, the structural integrity and optical clarity of a lens must be maintained. Maintenance of optical clarity requires that the lens not be obscured by foreign substances, that is, it must be substantially free of deposited substances such as cosmetics, microorganisms, body proteins, body lipids, and the like, which are well known to cause significant clarity problems. Maintenance of the structural integrity of a lens requires the avoidance of gross damage such as fracture, chipping, and both deep and wide scratches. Generally, a lens must be handled gently to avoid fracture or rupture and harmful scratching.
To remain safe in use a lens must fit comfortably in the eye so as to avoid irritation, inflammation, scratching and other damage to the eye, and it must allow the eye to receive sufficient oxygen and other essential substances to maintain normal function. Also, the lens must not be contaminated by microorganisms which will proliferate and infect the eye.
State of the art lens cleaning methods are generally chemical in nature. Contact lens cleaning solutions and compositions are known for both hard and soft contact lenses, and are described, for example, in U.S. Pat. Nos. 4,046,706; 4,013,576; 4,127,423; 4,104,187; 4,354,952 and 4,065,324. The solutions disclosed require soaking and/or heating and/or rubbing of the lens in the fingers or palm of the hand. The inconveniences of soaking and heating are obvious, e.g., additional utensils and equipment are used, a heat source is used, and the lens is not available for use for extended periods of time.
Two major problems created by rubbing in the hand include (1) the surface of the fingers or the hand may be too rough and scratch the lens, and frequently the skin may be soiled with materials which are likely to cause scratching; and (2) the skin is a major source of contamination of the lens by various microbes, oils, dust, chemicals, and the like, which are acceptable on the skin but not in the eye.
Another variation on lens cleaning solutions is disclosed in U.K. patent application No. 2,055,118A. This application describes a liquid cleaning composition containing an inorganic particulate abrasive and a surfactant. The compositions are limited in their usefulness to silicone-containing contact lenses and other harder lenses and are not suitable for soft contact lenses. When used to clean and remove deposits the methods suggested are immersing, spraying, rubbing, shaking and wiping, but no suggestion of using a non-woven fibrous mat is found. A similar method, disclosed in European Patent Application No. 0 063 472, teaches the use of a cleansing composition comprising organic polymer particulate matter suspended in a carrier for use in cleaning soft and hard contact lenses.
A further variation of lens cleaning methods is found in the use of a kit including sponges or synthetic foam of polyurethane such as are disclosed in U.S. Pat. Nos. 3,063,083 and 4,187,574. It has been found that the sponges of the art suffer from several deficiencies including a lack of abrasive power to remove deposits, a tendency to plug too rapidly with deposited material, a rapid and progressive loss of sterility and a relatively high cost. Another sponge-like product is available in Japan from Toyo Contact Lens Co., Ltd. Such a product is believed to be described in Japanese Kokai JP No. 82,105,427. This product is not known to be available in the United States at this time.
U.S. Pat. No. 4,357,173 describes a lens cleaning method which uses a "cleaning and polishing cloth" together with a polishing material. The cloth is only described as a "conventional polishing cloth" such as velveteen which to one in the art implies a woven cloth. Since the non-woven webs of the invention are not conventional, this reference does not recognize the outstanding properties of such webs.